title: The eccentric torque production capacity of the ankle, knee, and hip muscle groups in patients with unilateral chronic ankle instability.
abstract: OBJECTIVE
  The aim of this study was to investigate eccentric torque production capacity of the ankle, knee and hip muscle groups in patients with unilateral chronic ankle instability (CAI) as compared to healthy matched controls.
  
  
  METHODS
  In this case-control study, 40 participants (20 with CAI and 20 controls) were recruited based on convenient non-probability sampling. The average peak torque to body weight (APT/BW) ratio of reciprocal eccentric contraction of ankle dorsi flexor/plantar flexor, ankle evertor/invertor, knee flexor/extensor, hip flexor/extensor and hip abductor/adductor was determined using an isokinetic dynamometer. All subjects participated in two separate sessions with a rest interval of 48 to 72 hours. In each testing session, the torque production capacity of the ankle, knee, and hip muscle groups of only one lower limb was measured. At first, 3 repetitions of maximal eccentric-eccentric contraction were performed for the reciprocal muscles of a joint in a given movement direction. Then, the same procedure of practice and testing trials was repeated for the next randomly-ordered muscle group or joint of the same limb.
  
  
  RESULTS
  There was no significant interaction of group (CAI and healthy controls) by limb (injured and non-injured) for any muscle groups. Main effect of limb was not significant. Main effect of group was only significant for eccentric torque production capacity of ankle dorsi flexor and hip flexor muscle groups. The APT/BW ratio of these muscles was significantly lower in the CAI group than the healthy controls (P<0.05).
  
  
  CONCLUSIONS
  CAI is associated with eccentric strength deficit of ankle dorsi flexor and hip flexor muscles as indicated by reduction in torque production capacity of these muscles compared to healthy controls. This strength deficit appeared to exist in both the injured and non-injured limbs of the patients.
authors.affiliation: Musculoskeletal Rehabilitation Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Negahban
authors.forename: Aida
authors.initials: A
authors.lastname: Moradi-Bousari
authors.forename: Saeed
authors.initials: S
authors.lastname: Naghibi
authors.forename: Javad
authors.initials: J
authors.lastname: Sarrafzadeh
authors.forename: Mohammad-Jafar
authors.initials: MJ
authors.lastname: Shaterzadeh-Yazdi
authors.forename: Shahin
authors.initials: S
authors.lastname: Goharpey
authors.forename: Malihe
authors.initials: M
authors.lastname: Etemadi
authors.forename: Masood
authors.initials: M
authors.lastname: Mazaheri
authors.forename: Awat
authors.initials: A
authors.lastname: Feizi
keywords: Chronic Ankle Instability; Eccentric Strength; Lower Limb